Re: [patch]: fixing of pmtimer overflow that make Cx states time incorrect

alex.shi
2009-02-02T01:46:30Z

Yagui want to give a clear explanation to be used for commitment. So I resend
this again.

On most boxes the ACPI PM timer is 24-bit counter that runs on 3.579545MHz
clock. In such case the max C-state sleep time should be less than 4687ms when
it is used to record C2/C3 duration time.
But on some boxes the max C-state sleep time is more than 4687ms. In such
case the overflow happens and the C-state duration time can't be counted
accurately.

Use clocksource to get the C-state time instead of ACPI PM timer. and use
div64_u64 to convert US_TO_PM_TIME_TICKS in i386 mode.

Thanks
Alex

Asked-by: venkatesh.pallipadi@intel.com
Tested-by: Alex Shi <alex.shi@intel.com>
Signed-off-by: Alex Shi <alex.shi@intel.com>
Signed-off-by: Yakui.zhao <yakui.zhao@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

---

Index: linux-2.6.29-rc3/drivers/acpi/processor_idle.c
===================================================================
--- linux-2.6.29-rc3.orig/drivers/acpi/processor_idle.c
+++ linux-2.6.29-rc3/drivers/acpi/processor_idle.c
@@ -64,7 +64,8 @@
#define _COMPONENT ACPI_PROCESSOR_COMPONENT
ACPI_MODULE_NAME("processor_idle");
#define ACPI_PROCESSOR_FILE_POWER "power"
-#define US_TO_PM_TIMER_TICKS(t) ((t * (PM_TIMER_FREQUENCY/1000)) / 1000)
+#define US_TO_PM_TIMER_TICKS(t) div64_u64(\
+ (t * (PM_TIMER_FREQUENCY/1000)), 1000ULL)
#define PM_TIMER_TICK_NS (1000000000ULL/PM_TIMER_FREQUENCY)
#ifndef CONFIG_CPU_IDLE
#define C2_OVERHEAD 4 /* 1us (3.579 ticks per us) */
@@ -396,8 +397,9 @@ static void acpi_processor_idle(void)
struct acpi_processor *pr = NULL;
struct acpi_processor_cx *cx = NULL;
struct acpi_processor_cx *next_state = NULL;
- int sleep_ticks = 0;
- u32 t1, t2 = 0;
+ s64 sleep_ticks = 0;
+ ktime_t kt1, kt2;
+ s64 idle_time;

/*
* Interrupts must be disabled during bus mastering calculations and
@@ -544,14 +546,15 @@ static void acpi_processor_idle(void)

case ACPI_STATE_C2:
/* Get start time (ticks) */
- t1 = inl(acpi_gbl_FADT.xpm_timer_block.address);
+ kt1 = ktime_get_real();
/* Tell the scheduler that we are going deep-idle: */
sched_clock_idle_sleep_event();
/* Invoke C2 */
acpi_state_timer_broadcast(pr, cx, 1);
acpi_cstate_enter(cx);
/* Get end time (ticks) */
- t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);
+ kt2 = ktime_get_real();
+ idle_time = ktime_to_us(ktime_sub(kt2, kt1));

#if defined (CONFIG_GENERIC_TIME) && defined (CONFIG_X86)
/* TSC halts in C2, so notify users */
@@ -559,7 +562,7 @@ static void acpi_processor_idle(void)
mark_tsc_unstable("possible TSC halt in C2");
#endif
/* Compute time (ticks) that we were actually asleep */
- sleep_ticks = ticks_elapsed(t1, t2);
+ sleep_ticks = US_TO_PM_TIMER_TICKS(idle_time);

/* Tell the scheduler how much we idled: */
sched_clock_idle_wakeup_event(sleep_ticks*PM_TIMER_TICK_NS);
@@ -605,13 +608,14 @@ static void acpi_processor_idle(void)
}

/* Get start time (ticks) */
- t1 = inl(acpi_gbl_FADT.xpm_timer_block.address);
+ kt1 = ktime_get_real();
/* Invoke C3 */
/* Tell the scheduler that we are going deep-idle: */
sched_clock_idle_sleep_event();
acpi_cstate_enter(cx);
/* Get end time (ticks) */
- t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);
+ kt2 = ktime_get_real();
+ idle_time = ktime_to_us(ktime_sub(kt2, kt1));
if (pr->flags.bm_check && pr->flags.bm_control) {
/* Enable bus master arbitration */
atomic_dec(&c3_cpu_count);
@@ -624,7 +628,7 @@ static void acpi_processor_idle(void)
mark_tsc_unstable("TSC halts in C3");
#endif
/* Compute time (ticks) that we were actually asleep */
- sleep_ticks = ticks_elapsed(t1, t2);
+ sleep_ticks = US_TO_PM_TIMER_TICKS(idle_time);
/* Tell the scheduler how much we idled: */
sched_clock_idle_wakeup_event(sleep_ticks*PM_TIMER_TICK_NS);

@@ -1455,7 +1459,8 @@ static inline void acpi_idle_do_entry(st
static int acpi_idle_enter_c1(struct cpuidle_device *dev,
struct cpuidle_state *state)
{
- u32 t1, t2;
+ ktime_t kt1, kt2;
+ s64 idle_time;
struct acpi_processor *pr;
struct acpi_processor_cx *cx = cpuidle_get_statedata(state);

@@ -1476,14 +1481,15 @@ static int acpi_idle_enter_c1(struct cpu
if (pr->flags.bm_check)
acpi_idle_update_bm_rld(pr, cx);

- t1 = inl(acpi_gbl_FADT.xpm_timer_block.address);
+ kt1 = ktime_get_real();
acpi_idle_do_entry(cx);
- t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);
+ kt2 = ktime_get_real();
+ idle_time = ktime_to_us(ktime_sub(kt2, kt1));

local_irq_enable();
cx->usage++;

- return ticks_elapsed_in_us(t1, t2);
+ return idle_time;
}

/**
@@ -1496,8 +1502,9 @@ static int acpi_idle_enter_simple(struct
{
struct acpi_processor *pr;
struct acpi_processor_cx *cx = cpuidle_get_statedata(state);
- u32 t1, t2;
- int sleep_ticks = 0;
+ ktime_t kt1, kt2;
+ s64 idle_time;
+ s64 sleep_ticks = 0;

pr = __get_cpu_var(processors);

@@ -1533,18 +1540,19 @@ static int acpi_idle_enter_simple(struct
if (cx->type == ACPI_STATE_C3)
ACPI_FLUSH_CPU_CACHE();

- t1 = inl(acpi_gbl_FADT.xpm_timer_block.address);
+ kt1 = ktime_get_real();
/* Tell the scheduler that we are going deep-idle: */
sched_clock_idle_sleep_event();
acpi_idle_do_entry(cx);
- t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);
+ kt2 = ktime_get_real();
+ idle_time = ktime_to_us(ktime_sub(kt2, kt1));

#if defined (CONFIG_GENERIC_TIME) && defined (CONFIG_X86)
/* TSC could halt in idle, so notify users */
if (tsc_halts_in_c(cx->type))
mark_tsc_unstable("TSC halts in idle");;
#endif
- sleep_ticks = ticks_elapsed(t1, t2);
+ sleep_ticks = US_TO_PM_TIMER_TICKS(idle_time);

/* Tell the scheduler how much we idled: */
sched_clock_idle_wakeup_event(sleep_ticks*PM_TIMER_TICK_NS);
@@ -1556,7 +1564,7 @@ static int acpi_idle_enter_simple(struct

acpi_state_timer_broadcast(pr, cx, 0);
cx->time += sleep_ticks;
- return ticks_elapsed_in_us(t1, t2);
+ return idle_time;
}

static int c3_cpu_count;
@@ -1574,8 +1582,9 @@ static int acpi_idle_enter_bm(struct cpu
{
struct acpi_processor *pr;
struct acpi_processor_cx *cx = cpuidle_get_statedata(state);
- u32 t1, t2;
- int sleep_ticks = 0;
+ ktime_t kt1, kt2;
+ s64 idle_time;
+ s64 sleep_ticks = 0;

pr = __get_cpu_var(processors);

@@ -1644,9 +1653,10 @@ static int acpi_idle_enter_bm(struct cpu
ACPI_FLUSH_CPU_CACHE();
}

- t1 = inl(acpi_gbl_FADT.xpm_timer_block.address);
+ kt1 = ktime_get_real();
acpi_idle_do_entry(cx);
- t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);
+ kt2 = ktime_get_real();
+ idle_time = ktime_to_us(ktime_sub(kt2, kt1));

/* Re-enable bus master arbitration */
if (pr->flags.bm_check && pr->flags.bm_control) {
@@ -1661,7 +1671,7 @@ static int acpi_idle_enter_bm(struct cpu
if (tsc_halts_in_c(ACPI_STATE_C3))
mark_tsc_unstable("TSC halts in idle");
#endif
- sleep_ticks = ticks_elapsed(t1, t2);
+ sleep_ticks = US_TO_PM_TIMER_TICKS(idle_time);
/* Tell the scheduler how much we idled: */
sched_clock_idle_wakeup_event(sleep_ticks*PM_TIMER_TICK_NS);

@@ -1672,7 +1682,7 @@ static int acpi_idle_enter_bm(struct cpu